Investigation of nanofluid bubble characteristics under non-equilibrium conditions

Saeid Vafaei, Theodorian Borca-Tasciuc, Dongsheng Wen

Research output: Contribution to journalArticlepeer-review

13 Scopus citations

Abstract

We report experimental and theoretical investigations of the bubble characteristics during the oscillatory growth period for several nanofluids. The nanoparticles were found to affect liquid-gas and solid surface tensions, which modulated the bubble contact angle, radius of triple line, bubble volume and the dynamics of bubble growth. To increase the accuracy of the Young-Laplace equation predictions during the bubble growth in the oscillatory period, a new method multi-section bubble (MSB) approach was developed. In this method, the bubble was divided into n sections (i.e., n=1:. N) and the Young-Laplace equation was solved for each section individually. As N increases, within each section the effects of inertia force and viscosity become reduced comparing to that of the liquid-gas surface tension. Unlike the conventional Young-Laplace approach (i.e., N=1), the new approach is able to predict the bubble characteristics reliably in the following cases: (a) the oscillatory period when bubble is fluctuating; (b) the departure period when bubble is stretched upward, right before departure; and (c) the high shear stress condition when gas velocity is relatively high.

Original languageEnglish
Pages (from-to)116-124
Number of pages9
JournalChemical Engineering and Processing: Process Intensification
Volume86
DOIs
StatePublished - 1 Dec 2014
Externally publishedYes

Keywords

  • Bubble
  • Contact angle
  • Nanofluids
  • Nanoparticle
  • Solid surface tensions
  • Surface wettability
  • Triple line
  • Young-Laplace equation

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